Microsoft's stalled rollout of the Windows 10 October 2018 October Update, version 1809, has thrown a spanner in the works for new Arm-based Windows laptops from Samsung and Lenovo.

Windows 10 1809 is still on hold a month after Microsoft pulled it because it was deleting users photos and documents after installation. That was a major headache for the consumers concerned, but Microsoft withheld the release for most of its 700 million Windows, 10 users.

The first batch with Snapdragon 845 chips had great battery life but underwhelming performance for $1,000 machines.

The newer built-for-PC Snapdragon 850 chipset with clock speeds of up to 2.96GHz promised to address the performance gap.

Among this generation of Windows on Arm devices are Samsung's Galaxy Book2 and Lenovo's Yoga C630, which both became available this month in the lead-up to the Christmas shopping season.

But there's a problem, as Windows watcher Brad Sams points out on Petri. These new high-price Windows on Arm machines are being sold with a version of Windows 10 that Microsoft hasn't tested actually works with the Snapdragon 850 chipset.

Microsoft validates each version of Windows 10 support specific chips from Intel, AMD, and lately Qualcomm too.

Windows 10 1709 and 1803 were validated against Snapdragon 835. Windows 1809 is confirmed to support Snapdragon 850, but 1803 was never tested against this chip, as outlined in Microsoft's support pages.

And due to the critical bugs affecting Windows 10 1809, Microsoft appears to have thought it would be less risky to ship Windows 10 1803 to new Snapdragon 850 devices, even though it hasn't confirmed it works with them.

According to Sams' OEM sources, Microsoft's 1809 mess has created a "major headache", forcing them to ship products with untested software, which may mean downstream compatibility and support issues.

Sams found the Lenovo device at BestBuy and it was running Windows 10 1803, which means consumers won't see the features exclusive to 1809 that were promoted pre-launch.

Of course, Microsoft could rerelease Windows 10 1809 in the next few days, but some expected it would do that by the end of October.

The company has been testing fixed versions of the OS with Windows Insiders since it pulled the update on October 6.